Two-stroke internal combustion engine



Nov. 8, 1938. A. BOKEMULLER TWO-STROKE INTERNAL COMBUSTION ENGINE Filed July 8, 1936 5 Jnveni'or 0 Bo/rmuu El? 3r 100 90 a0 10 aa 50 40 30 2o 10 0 10 .20 so 4050 so 10 Q- -M A ramvzy Patented Nov. 8, 1938 UNITED STATES- PATENT orrlcs 'rwo-s'rnorm INTERNAL COMBUSTION ENGINE I Alfred Bokemiiller, Gaggenau-Baden, Germany, assignor, by mesne'assignments, to Sir W. G. Armstrong Whitworth & C0. (Engineers) Limited, Newcastle-upon-Tyne, England ,4 Claims.

Application July 8, 1936, Serial No. 89,538 In Germany July 8, 1935 engine. with any type .of internal combustion engine, is of particular significance in connection with While the invention is adapted for use two-stroke engine of the so-called Diesel type. An object of this invention is the provision of means for obtaining improved operation and efficiency of an internal combustion engine.

Another object of this invention is the pro vision of means for obtaining effective and reliable scavenging of the cylinder or cylinders of an internal combustion engine.

Still another object of this an internal combustion engine.

A further object of this invention is the provision of an improved method for effectivelyscavenging the cylinders of an internal combustion engine.

invention is the provision of improved valve and valve'seat for With the foregoing and other objects in view which will appear as the description proceeds,

the invention resides in the combination and ar- 1 rangement of parts and in the details of construction hereinafter described and claimed.

The invention is illustrated diagrammatically and by way of example on the accompanying drawing on which:

Figure lis an axial section of the cylinder and the piston and some adjacent parts of a twostroke Diesel-engine, the outlet-passage of which is controlled by the piston;

Figures 2 and 3 show each a portion otthe valve disk and the adjacent portion of the seat therefor, figures drawn to a greatly enlarged scale relatively to Fig.

Figure 4 shows details of Fig. 3, the scale being Referring to Fig. l, i denotes the cover of the cylinder, 2 denotes a cooling chamber in said cover, and 3 an inlet passage. at the inner end of which is located adisk-valve 4, the bottom-surface 5 of which constitutes the top of a combus- -tion space 8 located axially in the cover i.

communicating iuel supply channel I is likewise provided in said cover and may extend radially with respect to the axis of the cylinder andsomewhat obliquely. as shown. For best. operation possible and leads directly into theopen air.

With special regard to the valve disk and its seat, besides the usual conical seat 8, the latter is provided with a collar-like additional seating surface 9 (Figs. 2, 3 and 4) which co-operates with the rim zone 9* of the valve disk. In accordance with the length of the tightening surfaces 9, 9, the valve 4 will be opened earlier or later, but always only after the valve disk 5 has covered the path a (Fig. 4). This path a in Fig. 4 corresponds with the path a in the diagram shown in Fig. 5. From the curve I in this figure, it appears that he cam shaft has turned during that time through a crank-angle of 20 (from +80) and when then the opening of the valve passage commences at the point A the disk of the valve has already attained a considerable speed and in the-period of time t it will cover the path b.

sents for a two-stroke en ine operating after the oscillation principle beco e quite obvious if it is compared with the commencement of the stroke curve '11 indicated by a dotted line in Fig. 5. In the same section of time t the valve only coversthe path c. Similar are the conditions when the valve is being closed (point B of the curve I in Fig. 5). The valve is closed with a considerable speed-and its passage is already'blocked before the speed of the closing movement of the valve disk 5 has become considerably lower.

Referring again to Fig. l, it denotes the outlet of the machine and II denotes the working piston of the same. The inlet valve l is so controlled that it opens a predetermined time after the outlet slots havebeen uncovered by the pis-. ton, and a waste gas column of high velocity has arisen in the outlet pipe, producing a vacuum as high as possible in the cylinder. Furthermore, the outlet pipe has such dimensions, particularly such-a length, that a return'oi a portion of the gas column cannot hinder the scavenging air from entering into the cylinder. The 'necessary dimensions can readily be found by experiment. As shown in Fig. 1. a suitable device Illa may be provided in the outlet pipe iii which is so constructed as to partially prevent the return of gas into the cylinder. As can readily be seen, the device .lila allows almost totally unobstructed flow of the gases from the cylinder to the outer portion of the outlet pipe but will tend to catch and obstruct the passage of such gases when'returning to the cylinder.

Owing to the arrangement of the valve in the manner shown and described, the unreliable and variable portions of gas'movement at the com- The advantage which this operating valve pre- 2 mencement and at the end of the valve movement are dispensed with. This is another advantage which this invention presents to which may be added the further advantage that the valve disk forms together with the valve of the wall aperture a nozzle-like passage l2, viz., a passage having a nozzle-like sectional area which may well be utilized for a thorough dispersion or atomization of the fuel as it passes into the combustion chamber.

I wish to be understood that I consider it as lying within the scope of my invention if the combustion space 6 and the channel 1 are provided at another-suitable place in the cylinder head or at the cylinder, and the shape of said parts of the engine may be quite as desired. Instead of an injection nozzle an incandescence body, a spark plug or the like may be provided, the fact being that the invention can be used in connection with internal combustion engines of all constructional forms in which the entrance of the scavenging air and of the combustion air is effected or assisted by the sucking action of the escaping exhaust gases.

In this respect, by way of example I refer e pecially to Fig. 6 in which is represented a twostroke internal combustion engine having an.in-- let valve l3 and an outlet valve l4 in the cylinder head. Also in this example the inlet passage I5 is as short as possible and communicates directly with the open air, whereas the outlet passage I6 communicates with a nozzle-like exhaust pipe I1.

While I have herein shown and described only certain embodiments of certainfeatures of my present invention it is to be understood that they are to be regarded merely as illustrative and that I do not intend to limit myself thereto except as may be required by the following claims.

I claim:

,1. In a two-stroke cycle internal combustion engine, in combination, a cylinder provided with an exhaust orifice, means for opening saidexhaust orifice to permit the burnt gases to be discharged from the cylinder at high velocity and as a mass, leaving a high depression behind them, an inlet passage communicating with the cylinder, a valve adapted to open and close said inlet passage, comprising a disk, and a seating surface therefor positioned transversely with respect to the direction of motion of said disk, said seating surface having a portion extending parallel to the direction of motion of said disk, whereby said valve opens only after said disk has travelled a predetermined distance, and

. means for opening said inlet valve when the said depression has been created and a suction effect is exerted at the inlet orifice.

2. In a two-stroke cycle internal combustion engine, in combination, a cylinder provided with an exhaust orifice, a valve adapted to open and close said orifice said valve comprising a disk,

.and a seating surface therefor positioned transversely with respect to the direction of motion of the said disk, said seating surface having a portion extending parallel to the direction of motion of said disk, whereby said valve opens only after said disk has travelled a predetermined distance, means for opening said exhaust valve to permit the burnt gases to be discharged from the cylinder at high velocity and as a mass,Jeaving a high depression behind them, an inlet passage communicating with the cylinder, a valve adapted to open and close said inlet passage, and means for opening said inlet valve when the said depression has been created and a suction effect is exerted at the inlet orifice.

3. In a two-stroke cycle internal combustion engine, in combination, a cylinder provided with an exhaust orifice, a valve adapted to open and close said orifice, means for opening said exhaust valve to permit the burnt gases to be discharged from the cylinder at high velocity and as a mass, leaving a high depression behind them, an inlet passage communicating with the cylinder, a valve adapted to open and close said inlet passage, and means for opening said inlet valve when the said depression has been created and a suction effect is exerted at the inlet orifice, each of said valves comprising a disk, and a seating surface therefor positioned transversely with respect to the direction of motion of said disk, said seating surface having a portion'extending parallel to the direction of motion of said disk, whereby said valve opens only after said disk has travelled a predetermined distance.

i. In a two-stroke cycle internal combustion engine in combination, a cylinder provided with an exhaust orifice, means for opening said exhaust orifice to permit the burnt gases to be discharged from the cylinder at high velocity and as a mass, leaving a high depression behind them, an inlet passage communicating directly with the atmosphere and with the cylinder, a valve adapted to open and close said inlet passage, com-.

prising a disk, and a seating surface therefor positioned transversely with respect to the direction of motion of said disk, said seating surface having a portion extending parallel to the direction of motion of said disk, whereby said valve opens only after said disk has travelled a predetermined distance, and means for opening said inlet valve when the said depression has been created and a suction effect is exerted at the inlet orifice.

ALFRED BOKEMfiLLER. 

